US3873414A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the treatment of black liquor of cellulosic pulp wherein oxidation is performed both before and after black liquor concentration
Assignee: Air Liquide SA
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Filing: 1974-02-22
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Granted: 1975-03-25
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Expires: 1994-02-22
Abstract
Abstract A process for the treatment of black liquor in which in a first oxidation stage there is blown into dilute black liquor a quantity of oxygen ranging from 0.5 to 1 times that theoretically necessary for oxidizing the sodium sulphide to sodium thiosulphate and, in a second oxidation stage, there is blown into black liquor after it has been concentrated a quantity of oxygen greater than that necessary for converting the residual sodium sulphide to sodium thiosulphate. The process is applicable to the recovery of chemical elements, notably from Kraft pulps.
Inventors
- 👤 Jacques Rocher
- 👤 Masamichi Hotta
- 👤 Mamoru Inomata
- 👤 Kazuo Hanabusa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:57
CPC Classifications
D; D21; D21C; D21C11/00; D21C11/0057; Y; Y10; Y10S; Y10S210/00; Y10S210/928; Y10S423/00; Y10S423/03
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
208 words
In a process for the treatment of black liquor formed during the pulping of cellulosic materials by the Kraft process, so as to oxidize sulfide present in the black liquor to facilitate recovery of useful chemical elements which the black liquor contains, comprising: blowing oxygen into the black liquor removed from the Kraft process after separation of the pulp therefrom, and then concentrating by vaporization the oxygen treated black liquor to obtain a relatively concentrated black liquor of about 1.5 to 15 g/l sulfide, the improvement comprising: effecting the blowing of oxygen into the black liquor in two separate stages; the first said stage being prior to said concentration step and wherein the quantity of oxygen blown into the black liquor is from 0.5 to 1 times that quantity of oxygen theorectically necessary to convert by oxidation to sodium thiosufate that sodium sulfide present, whereby part of the sodium sulfide in the black liquor is oxidized to sodium thiosulfate; the second said stage being after said concentration step and wherein the quantity of oxygen blown into the black liquor is about 1.1 to 1.5 times greater than that quantity of oxygen theoretically necessary to convert by oxidation to sodium thiosulfate the residual sodium sulfide in the black liquor.
Claim 2
Dependent Claim
208 words
In a process for the treatment of black liquor formed during the pulping of cellulosic materials by the Kraft process, so as to oxidize sulfide present in the black liquor to facilitate recovery of useful chemical elements which the black liquor contains, comprising: blowing oxygen into the black liquor removed from the Kraft process after separation of the pulp therefrom, and then concentrating by vaporization the oxygen treated black liquor to obtain a relatively concentrated black liquor of about 1.5 to 15 g/l sulfide, the improvement comprising: effecting the blowing of oxygen into the black liquor in two separate stages; the first said stage being prior to said concentration step and wherein the quantity of oxygen blown into the black liquor is from 0.5 to 1 times that quantity of oxygen theorectically necessary to convert by oxidation to sodium thiosufate that sodium sulfide present, whereby part of the sodium sulfide in the black liquor is oxidized to sodium thiosulfate; the second said stage being after said concentration step and wherein the quantity of oxygen blown into the black liquor is about 1.1 to 1.5 times greater than that quantity of oxygen theoretically necessary to convert by oxidation to sodium thiosulfate the residual sodium sulfide in the black liquor.
Claim 3
Dependent Claim
28 words
A process according to claim 1, wherein the oxygen which is blown into the said black liquor in the first oxidation stage is formed by vaporizing liquid oxygen.
Claim 4
Dependent Claim
29 words
A process according to claim 1, wherein the oxygen which is blown into the said black liquor in the first oxidation stage is in the form of oxygen-enriched air.
Claim 5
Dependent Claim
28 words
A process according to claim 1, wherein the oxygen which is blown into the said black liquor in the first oxidation stage is in the form of air.
Claim 6
Dependent Claim
28 words
A process according to claim 1, wherein the oxygen which is blown into the said black liquor in the second oxidation stage is obtained by vaporizing liquid oxygen.
Claim 7
Dependent Claim
29 words
A process according to claim 1, wherein the oxygen which is blown into the said black liquor in the second oxidation stage is in the form of oxygen-enriched air.
Claim 8
Dependent Claim
28 words
A process according to claim 2, wherein the oxygen which is blown into the said black liquor in the second oxidation stage is obtained by vaporizing liquid oxygen.
Claim 9
Dependent Claim
29 words
A process according to claim 3, wherein the oxygen which is blown into the said black liquor in the second oxidation stage is in the form of oxygen-enriched air.
Claim 10
Dependent Claim
175 words
IN A PROCESS FOR THE TREATMENT OF BLACK LIQUOR SEPARATED FROM CELLULOSIC PPULP PRODUCED BY THE KRAFT PROCESS, SO AS TO OXIDIZE SULPHIDE PRESENT IN THE BLACK LIQUOR WITH A VIEW TO RECOVERING USEFUL CHEMICAL ELEMENTS WHICH THE BLACK LIQUOR CONTAINS, THE STEPS COMPRISING A. IN A FIRST OXIDATION STAGE, BLOWING INTO BLACK LIQUOR LEAVING THE KRAFT PROCESS, 0.5 TO 1 TIMES THE QUANTITY OF OXYGEN NECESSARY TO THEORETHICALLY OXIDIZE ALL THE SODIUM SULFIDE TO SODIUM THIOSULFATE TO THEREBY OXIDIZE A PORTION OF THE SODIUM SULFPHIDE PRESENT IN THE BLACK LIQUOR; B. THEN CONCENTRATING THE DILUTE BLACK LIQUOR OF ABOUT 1.5 TO 75 B. THEN CONCENTRATING THE DILUTE BLACK LIQUOR TO GIVE A CONCENTRATED BLACK LIQUOR OF ABOUT 1.5 TO 15 G/L SULFIDE; AND, C. IN A SECOND OXIDATION STAGE FOLLOWING SAID CONCENTRATING STEP, BLOWING INTO THE SAID CONCENTRTED BLACK LIQUOR A QUANTITY OF OXYGEN WHICH IS ABOUT 1.1 TO 1.5 TIMES GREATER THAN THAN QUANTITY OF OXYGEN NECESSARY TO CONVERT BY OXIDATION TO SODIUM THIOSULPHATE THE RESIDUAL SULPHIDE IN THE SAID CONCENTRATED BLACK LIQUOR.
Claim 11
Dependent Claim
175 words
IN A PROCESS FOR THE TREATMENT OF BLACK LIQUOR SEPARATED FROM CELLULOSIC PPULP PRODUCED BY THE KRAFT PROCESS, SO AS TO OXIDIZE SULPHIDE PRESENT IN THE BLACK LIQUOR WITH A VIEW TO RECOVERING USEFUL CHEMICAL ELEMENTS WHICH THE BLACK LIQUOR CONTAINS, THE STEPS COMPRISING A. IN A FIRST OXIDATION STAGE, BLOWING INTO BLACK LIQUOR LEAVING THE KRAFT PROCESS, 0.5 TO 1 TIMES THE QUANTITY OF OXYGEN NECESSARY TO THEORETHICALLY OXIDIZE ALL THE SODIUM SULFIDE TO SODIUM THIOSULFATE TO THEREBY OXIDIZE A PORTION OF THE SODIUM SULFPHIDE PRESENT IN THE BLACK LIQUOR; B. THEN CONCENTRATING THE DILUTE BLACK LIQUOR OF ABOUT 1.5 TO 75 B. THEN CONCENTRATING THE DILUTE BLACK LIQUOR TO GIVE A CONCENTRATED BLACK LIQUOR OF ABOUT 1.5 TO 15 G/L SULFIDE; AND, C. IN A SECOND OXIDATION STAGE FOLLOWING SAID CONCENTRATING STEP, BLOWING INTO THE SAID CONCENTRTED BLACK LIQUOR A QUANTITY OF OXYGEN WHICH IS ABOUT 1.1 TO 1.5 TIMES GREATER THAN THAN QUANTITY OF OXYGEN NECESSARY TO CONVERT BY OXIDATION TO SODIUM THIOSULPHATE THE RESIDUAL SULPHIDE IN THE SAID CONCENTRATED BLACK LIQUOR.
References Cited (Backward Citations)
US3549314A
Cited
US3709975A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |